unable to acces outlook.com mailbox due to mailboxintransitexception error

Hi,

I urgently need help accessing my personal Outlook.com mailbox.

I can successfully sign in to my Microsoft account at account.microsoft.com, so my username and password are working correctly. However, when I try to open Outlook/mail, my mailbox does not load. It keeps loading indefinitely or I receive an error named "mailboxintransitexception"

The same problem occurs on multiple devices and browsers, including my computer and my phone, so it does not appear to be a browser, cache, or device issue.

I have already tried the usual troubleshooting steps, including different browsers/devices and signing out and back in, without success.

I also contacted Microsoft Support via chat, but unfortunately the issue was not resolved. I was previously given information suggesting that there may be a server-side issue or that my mailbox/account is being moved to another server.

Important: I am able to access my Microsoft account itself. The problem is specifically that I cannot access my Outlook.com mailbox.

This mailbox is very important to me and I currently have no access to my emails. Could someone please advise what could cause this and, if this is a server-side/mailbox issue, how I can get it escalated to the appropriate Outlook.com technical team?

Thank you very much for any help.